Tissue anchor for securing tissue layers

ABSTRACT

Tissue anchors comprise a woven filament braid body having an elongated tubular configuration and a foreshortened configuration where proximal and distal ends of the body expand radially into double-walled flange structures while leaving a cylindrical saddle region therebetween. The tissue anchors are deployed through penetrations between adjacent tissue layers, where the flanges engage the outer surfaces of the tissue layers and the saddle region resides within the tissue penetrations.

CROSS-REFERENCES TO RELATED APPLICATIONS

This application claims the benefit of provisional application61/052,460, filed on May 12, 2008, the full disclosure of which isincorporated herein by reference. The disclosure of this application isrelated to those of Ser. No. 12/427,254, filed on the same day as thepresent application.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates generally to medical methods and devices.In particular, the present invention relates to tissue anchors andmethods for their use in fastening adjacent tissue layers in medicalprocedures.

Tissue approximation is useful in many medical procedures for a varietyof purposes. In the broadest definition, tissue apposition may beperformed by a number of conventional procedures, such as suturing,gluing, energy-mediated fusion, and the like. Of particular interest tothe present invention, however, is the use of tissue fasteners which arepositioned through penetrations in adjacent tissue layers and deployedto physically hold or anchor the tissue layers together.

A number of tissue-anchoring systems have been devised over the years.Many prior art tissue anchors include expandable cage structures, oftenreferred to as malecotts, or “molybolts,” at opposite ends of a shaft,where the cages are expanded and deployed on each side of the layeredtissues to be anchored together. One exemplary tissue anchor employingexpandable structural elements on each side of a shaft for anchoring theesophagus to the stomach wall is described in commonly-owned, copendingU.S. patent publication no. 2005/0228413. In some instances, themechanical tissue fasteners may provide or define a central lumen orpassage, typically to allow for drainage from one body lumen or cavityinto another. Such fasteners are often referred to as “stents,” with anexemplary stent for draining a pseudocyst described in U.S. Pat. No.6,620,122. The '122 stent has a barbell-like configuration with opencuffs at each end. The cuffs are not reinforced and do not providesignificant strength for holding adjacent tissue structures together,particularly when the tissue structures tend to separate as the patientmoves about.

While usable for many purposes, the tissue anchors of the prior art haveoften been either too rigid, providing good attachment but presentingsubstantial risk of tissue necrosis or adhesion, or too weak, presentinglittle risk of tissue damage but allowing leakage and movement at thepoint of tissue penetration.

Thus, for these reasons, it would be beneficial to provide alternativeor improved tissue anchors and methods for their deployment and use,where the anchors can provide firm attachment of tissue while minimizingthe risk of necrosis and other damage to the tissue. The tissue anchorsshould preferably be suitable for attachment both with and without acentral lumen for fistula formation. The tissue anchors should bedeliverable endoscopically to a wide variety of body lumens for a widevariety of purposes. Additionally, it would be desirable if the tissueanchors were removable, both during initial implantation procedures aswell as in a subsequent procedure(s) many weeks, months, or even yearsfollowing the initial implantation. At least some of these objectiveswill be met by the inventions described hereinbelow.

2. Description of the Background Art

US 2003/069533 describes an endoscopic transduodenal biliary drainagesystem which is introduced through a penetration, made by a trans-orallyadvanced catheter having a needle which is advanced from the duodenuminto the gall bladder. U.S. Pat. No. 6,620,122 describes a system forplacing a self-expanding stent from the stomach into a pseudocyst usinga needle and an endoscope. US 2005/0228413, commonly assigned with thepresent application, describes a tissue-penetrating device for endoscopyor endosonography-guided (ultrasonic) procedures where an anchor may beplaced to form an anastomosis between body lumens, including theintestine, stomach, and gallbladder. See also U.S. Pat. No. 5,458,131;U.S. Pat. No. 5,495,851; U.S. Pat. No. 5,944,738; U.S. Pat. No.6,007,522; U.S. Pat. No. 6,231,587; U.S. Pat. No. 6,655,386; U.S. Pat.No. 7,273,451; U.S. Pat. No. 7,309,341; US 2004/0243122; US2004/0249985; US 2007/0123917; WO 2006/062996; EP 1314404 Kahaleh et al.(2006) Gastrointestinal Endoscopy 64:52-59; and Kwan et al. (2007)Gastrointestinal Endoscopy 66:582-586.

BRIEF SUMMARY OF THE INVENTION

Tissue anchors according to the present invention comprise a body formedfrom a woven filament braid. The filament will typically be a metalwire, more typically being a nickel-titanium or other super-elastic orshape memory metal wire. Alternatively, in cases where elasticity isless critical, a filament could be formed from a polymeric material,such as polypropylene, polyethylene, polyester, nylon, PTFE, or thelike. In some cases, a bioabsorbable or bio-degradable material,typically a biodegradable polymer, such as poly-L-lactic acid (PLLA),could find use.

The body will have both an elongated tubular configuration and aforeshortened configuration where proximal and distal ends of the bodyexpand radially (as the body is foreshortened) into double-walled flangestructures. Such “double-walled flange structures” are formed as aportion of the body, typically an end-most portion but optionally someportion spaced inwardly from the end, moves inwardly (toward the middle)so that a pair of adjacent body segments within the portion are drawntogether at their bases so that a midline or a crest line bends andexpands radially to form a pair of adjacent annular rings which definethe double-walled flange structure. After such foreshortening anddeployment of the double-walled flange structures, the body will furtherhave a cylindrical saddle region between the flange structures. When theanchor is deployed in tissue, the flange structures engage the outersurfaces of adjacent tissue layers and the saddle region typicallyresides within a penetration through the tissue layers.

When formed from shaped memory metal wires, such as nitinol or eligiloy,the wires will have a relatively small diameter, typically in the rangefrom 0.001 inch to 0.02 inch, usually from 0.002 inch to 0.01 inch,where the braid will include from as few as 10 to as many as 200 wires,more commonly being from 20 wires to 100 wires. In exemplary cases, thewires will be round having diameters in the range from 0.003 into the0.007 inch with a total of from 24 to 60 wires. The wires are braidedinto a tubular geometry by conventional techniques, and the tubulargeometry will be heat-treated to impart the desired shape memory.Usually, the braided tube will be formed into the desired final(deployed) configuration with the flanges at each end. Such a flangedconfiguration will then be heat set or formed into the braid so that, inthe absence of a radially constraining or axially elongating force, theanchor will assume the foreshortened configuration with the flanges ateach end. Such foreshortened-memory configurations will allow the anchorto be delivered in a constrained configuration (either radially oraxially elongated) and thereafter released from constraint so that thebody assumes the flanged configuration at the target site.

In alternative embodiments, however, the woven filament braid will beheat set into the elongated tubular configuration and shifted into theforeshortened, flanged configuration by applying an axial compressiveforce. Such axial compression will foreshorten and radially expand theflanges. The flanges may be preferentially formed by providing sleeves,tubes, rods, filaments, tethers, or the like, which apply force to thetube to create the flanges while leaving the cylindrical saddle regionunexpanded or expanded to a lesser degree. Optionally, the body may haveweakened regions, reinforced regions, or be otherwise modified so thatthe desired flange geometries are formed when a force is applied tocause axial foreshortening.

The tissue anchors will be adapted to be delivered by a delivery device,typically an endoscopic delivery catheter, usually having a smalldiameter in the range from 1 mm to 8 mm, usually from 2 mm to 5 mm.Thus, the elongated tubular configuration of the anchor body willusually have a diameter less than that of the catheter diameter, usuallyfrom 0.8 mm to 7.5 mm, more usually from 0.8 mm to 4.5 mm, where thedouble-walled flanged structures will be expandable significantly,usually being in the range from 3 mm to 70 mm, more usually in the rangefrom 5 mm to 40 mm. The cylindrical saddle region of the anchor willoften not increase in diameter during deployment, but may optionallyincrease to a diameter from 2 mm to 50 mm, more usually from 5 mm to 20mm. When present, the lumen or passage through the deployed tissueanchor can have a variety of diameters, typically from as small as 0.2mm to as large as 40 mm, more usually being in the range from 1 mm to 20mm, and typically having a diameter which is slightly smaller than theexpanded diameter of the cylindrical saddle region. The length of thebody may also vary significantly. Typically, when in the elongatedtubular configuration, the body will have a length in the range from 7mm to 100 mm, usually from 12 mm to 70 mm. When deployed, the body willbe foreshortened, typically by at least 20%, more typically by at least40% and often by 70% or greater. Thus, the foreshortened length willtypically be in the range from 2 mm to 80 mm, usually in the range from2.5 mm to 60 mm, and more usually being in the range from 3 mm to 40 mm.

The body of the tissue anchor may consist of the woven filament braidwith no other coverings or layers. In other instances, however, thetissue anchor may further comprise a membrane or other covering formedover at least a portion of the body. Often, the membrane is intended toprevent or inhibit tissue ingrowth to allow the device to be removedafter having been implanted for weeks, months, or longer. Suitablemembrane materials include polytetrafluoroethylene (PTFE), expanded PTFE(ePTFE), silicone, polypropylene, urethane polyether block amides(PEBA), polyethyleneterephthalate (PET), polyethylene, C-Flex®thermoplastic elastomer, Krator® SEBS and SBS polymers, and the like.

Such membranes may be formed over the entire portion of the anchor bodyor only a portion thereof, may be formed over the exterior or interiorof the body, and will typically be elastomeric so that the membraneconforms to the body in both the elongated and foreshortenedconfigurations. Optionally, the membrane may be formed over only thecentral saddle region, in which case it would not have to be elastomericwhen the central saddle region does not radially expand.

The strength of the double-walled flanged structures will depend on thenumber, size, stiffness, and weave pattern(s) of the individual wiresused to form the tubular anchor body. For example, a design with a largenumber of nitinol wires, for example 48, but a relatively small wirediameter, for example 0.006 inches, will form a braid structure with asaddle region which remains flexible and double-walled flanges which arerelatively firm. Use of fewer wires, for example 16, and a larger wirediameter, for example 0.016 inches, will form a braid structure with arelatively rigid saddle region and relatively stiff, non-flexibleflanges. Usually, the more flexible design is desirable. In particular,it is preferred that the double-walled flange structures have apreselected bending stiffness in the range from 1 g/mm to 100 g/mm,preferably in the range from 4 g/mm to 40 g/mm. Similarly, it ispreferred that the central saddle region have a preselected bendingstiffness in the range from 1 g/mm to 100 g/mm, preferably from 10 g/mmto 100 g/mm.

The bending stiffness of the flange can be determined by the followingtest. The distal flange is secured in a fixture. The outer diameter ofthe flange is pulled in a direction parallel to the axis of the tissueanchor using a hook attached to a Chatillon force gage. The saddle ofanchor is held in a hole in a fixture and force (grams) and deflection(mm) are measured and recorded. The bending stiffness of the flange canbe determined by the following test. The distal flange is secured in afixture. The outer diameter of the flange is pulled in a directionperpendicular to axis of the tissue anchor using a hook attached to aChatillon force gage. The saddle of anchor is held in a hole in afixture and force (grams) and deflection (mm) are measured and recorded.

While it will usually be preferred to form the self-expanding anchorbodies from shape memory alloys, other designs could employ elastictethers which join the ends of the body together. Thus, the bodies couldhave a low elasticity, where the force for axially compressing the endscomes from the elastic tethers. Such designs may be particularlysuitable when polymeric or other less elastic materials are being usedfor the body of the anchor.

In still other embodiments, the tissue anchors may comprise a lock whichmaintains the body in a foreshortened configuration. For example, thelock may comprise a rod or a cylinder within the body which latches toboth ends of the body when the body is foreshortened. Alternatively, thelock could comprise one, two, or more axial members which clamp over thelumen of the anchor body when the body is foreshortened.

As a still further option, the tissue anchor could comprise a sleeveformed over a portion of the cylindrical saddle region. The sleeve willboth maintain the diameter of the central saddle region and will limitthe inward extension of the flanges, help forming the flanges as theanchor body is axially foreshortened.

In still other embodiments, the body of the tissue anchor will beexpanded by applying an axial compression to the ends of the body (i.e.,drawing the ends toward each other, not by self-expansion). Usually, thebody in such embodiments will be pre-shaped or pre-formed to assume itselongated tubular configuration when not subjected to axial compression.Only by applying an axially compressive force will the flanges be formedat the ends. The force may be applied in a variety of ways. Mostcommonly, at least one axial member will be attached to one end of thebody, where the axial member can be pulled to foreshorten the body. Theaxial member may comprise a plurality of tethers. In a particularexample, the tethers will lie over the exterior of the body in thesaddle region lying within a lumen of the body within the flangeregions. Alternatively, the axial member may comprise a rod or cylinderwhich is disposed within the lumen of the body. In particular, thecylinder may be attached at one end of the body and pulled toward theother end to deploy the flanges. When the body is fully deployed, thecylinder may be attached to the other end of the body, thus providing anopen lumen through the body. In those embodiments where the flanges aredeployed by applying an axial compression to the body, it will usuallybe necessary to provide a lock to hold the body in the foreshortenedconfiguration. A variety of specific lock structures are describedhereinbelow.

In another aspect of the present invention, systems for delivering thetissue anchor are provided. The self-expanding tissue anchors may bedelivered using a delivery catheter comprising a sheath which covers thetissue anchor body, or a mandrel which extends through a central lumenof the anchor body, to hold the body in its elongated tubularconfiguration. By then retracting the sheath or advancing the tissueanchor relative to the sheath, the body of the anchor is released fromconstraint and the flanges are allowed to radially expand. For use withthe tissue anchors which require the application of an axial force fordeployment, the delivery catheter will comprise an actuator whichreleasably holds the tissue anchor and which includes a mechanism forengaging and pulling (axially tensioning) the axial member to expand theflanges and deploy the anchor.

In still other aspects of the present invention, methods forapproximating tissue comprising forming aligned penetrations in two ormore adjacent tissue layers. The tissue anchor is then advanced throughthe penetrations, where the tissue anchor comprises a body formed fromthe woven filament braid. The body is in an elongated tubularconfiguration while being advanced and is subsequently foreshortened tocause a distal end and a proximal end of the body to each deform intodouble-walled flange structures on opposite sides of the adjacent tissuelayers. A cylindrical saddle region remains on the anchor body betweenthe deployed flanges, where the flanges are able to press against thetissue layers to provide the approximating force. Typically, the bodywill be foreshortened to a degree selected to apply sufficient pressureto the tissues to hold them together without causing significant tissueinjury or necrosis. Usually, the applied pressure will be in the rangefrom 0.005 g/mm² to 5 g/mm², usually from 0.2 g/mm² to 1 g/mm².

The methods of the present invention are useful for holding a widevariety of adjacent tissue layers together, where the tissues aretypically selected from the group consisting of the esophagus, stomach,duodenum, small intestine, large intestine, bile duct, pancreatic duct,gallbladder, pancreas, pancreatic pseudocyst, liver, diaphragm, and crusmuscle and adjoining tissues. The anchor is typically formed andadvanced by positioning a catheter near a target location on the tissuewall within a body lumen. The penetrating element is then advanced fromthe catheter to form the penetrations, and the catheter is advancedthrough the penetrations to position the tissue anchor therethroughprior to foreshortening. Foreshortening may comprise either of theapproaches described above. That is, foreshortening may comprisereleasing the elongated tubular body from constraint so that the flangesself-expand. Alternatively, the foreshortening may comprise applying anaxial tension to the anchor body to draw the ends closer, thus deployingthe flanges radially outwardly.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a first exemplary tissue anchor constructed inaccordance with the principles of the present invention.

FIGS. 1A-1C illustrate formation of a double-walled anchor structure inan end of the tissue anchor.

FIGS. 2A-2C illustrate alternate distal end constructions of the tissueanchor of FIG. 1, taken along line 2-2 thereof.

FIGS. 3A-3F illustrate alternative deployments and modifications to theexemplary tissue anchor of FIG. 1.

FIGS. 4A and 4B illustrate the tissue anchor employing elastic tethersfor deployment.

FIGS. 5A and 5B illustrate a tissue anchor having latching elements.

FIGS. 6A and 6B illustrate a tissue anchor having tethers for applyingan axial force for foreshortening and deployment.

FIGS. 7A and 7B illustrate a tissue anchor having an internal cylinderfor applying an axially compressive force and latching the anchor in itsdeployed configuration.

FIGS. 8A and 8B illustrate another stent design having tethers to effectforeshortening and radial expansion.

FIG. 9 illustrates a stent having a one-way flow valve according to thepresent invention.

FIG. 10 illustrates a patient's anatomy including cross sections of thegallbladder and duodenum.

FIG. 11 illustrates an exemplary system for penetrating the intestinaland gallbladder walls in accordance with the principles of the presentinvention.

FIGS. 12A-12G illustrate the method of the present invention forestablishing a flow path between the gallbladder and the intestines inaccordance with the principles of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

As shown in FIG. 1, tissue anchor 10 constructed in accordance with theprinciples of the present invention comprises a body 12 having caps 14at each end thereof. The body 12 comprises a woven filament braid, asdiscussed in more detail above, and is illustrated in its elongatedtubular configuration. In this particular embodiment, the body 12 willbe formed from a super elastic material, typically nitinol or eligiloy,and will be heat set, so that in the absence of radial constraint or anaxially elongating force, the body will revert to its memoryconfiguration having double-walled flanges formed at each end. One ofthe flanges 16 is shown in broken line in FIG. 1, while FIGS. 3A-3Fillustrate various configurations of the flanges 16.

Referring now to FIGS. 1A-1C, the double-walled flange structure 16forms as the end of tubular body 12 axially foreshortens. Initially, theend of the tubular body 12 is maintained in its tubular configuration,as shown in FIG. 1A. Maintenance of the tubular configuration can beachieved in various ways, such as using an external tubular sheath orother restraint (not shown), by using a mandrel or other elongatestructure which is advanced through an inside lumen or passage 18 of thebody to engage the end and/or occupy the entire lumen in order tomaintain the tubular configuration, or the like. Once the constraint isremoved, the pre-formed or memory shape of the double-walled flangestructure will begin to form, as shown in FIG. 1B. The end of thetubular structure 12 will move toward the middle of the tubularstructure, as shown by the arrow in FIG. 1B, and a preformed ridge 17will appear, eventually collapsing into the double-walled flangestructure 16 as illustrated in FIG. 1C. While the above description isdirected at embodiments where the tubular body 12 has been preformed tohave the double-walled flange structure 16 as part of its memory, thegeneral change in geometry will also be true for those anchors where anaxially compressive force must be applied in order to deploy theflanges. In such cases, the tubular body may have preformed scoring orother weakened regions which preferentially allow the woven braid tobend in the manner illustrated in FIGS. 1A-1C.

The end caps 14 will be provided when it is desired to constrain the endof the anchor body 12 to prevent the end(s) from expanding. In someinstances, the end cap 14 will have a solid face, as shown in FIG. 2A,which will close the inside lumen or passage 18 to prevent or inhibitthe flow of body fluids therethrough. Alternatively, the end cap 14 amay be formed with a passage 20 therethrough to allow for its flowthrough lumen 18 (FIG. 2B). In a still further alternate embodiment, asshown in FIG. 2C, the tissue anchor 10 may not include any end caps,allowing the end to expand in certain embodiments.

Referring now to FIGS. 3A through 3F, various deployment configurationsfor the tissue anchor 10 will be described (where the tissue anchor 10is assumed to have the same elongated starting length in eachillustrated deployment). In FIG. 3A, the flanges 16 expand radiallywhile a central saddle region 22 does not expand. In FIG. 3B, thecentral saddle region 22 does not significantly expand but has asomewhat greater deployed length than that of the embodiment of FIG. 3A,resulting in flanges 16 having a slightly smaller diameters. FIG. 3Balso illustrates a covering or membrane 24 over the entire exterior ofthe tissue anchor 10, thus inhibiting tissue ingrowth and/or minimizingfluid leakage when the anchor is implanted. In FIG. 3C, tissue anchor 10includes the open end caps 14 a providing an open lumen 18 therethrough.In FIG. 3D, a tissue anchor 10 having a central saddle region 22 with asignificantly expanded diameter is illustrated. In FIG. 3E, the tissueanchor 10 having open ends 26 (that is, they are free from the end capas illustrated in FIG. C) is illustrated. Passages 26 are shown to havegenerally the same diameter as the tubular body 22 in its non-deployedconfiguration. In contrast, in FIG. 3F, open ends 28 are shown havingdiameters which are significantly greater than the non-deployed diameterof the anchor body. Similarly, the central saddle region 22 of FIG. 3Fis also significantly greater than the diameter of the non-deployedtissue anchor. It will be appreciated that the tissue anchors of thepresent invention may have a wide variety of configurations withdifferent lengths, saddle region diameters, flange diameters, openlumens, closed lumens, membrane-covered surfaces, partiallymembrane-covered surfaces, and the like.

Referring now to FIGS. 4A and 4B, a tissue anchor 30 having analternative construction is illustrated. The body 32 of tissue anchor 30is not pre-shaped, forming the enlarged flanges as a result of axialshortening. For example, elastic tethers 34 are provided which apply theaxially compressive force to foreshorten the ends and form double-walledflanges 36, as illustrated in FIG. 4B. The resulting shape may becontrolled by providing reinforcement over a central saddle region 38 toprevent that region from axially foreshortening and/or radiallyexpanding. Alternatively, the central saddle region 38 could be fusedtogether to prevent deformation. In the device of FIGS. 4A and 4B, thetissue anchor can be deployed through a tissue tract while the exterioris radially constrained or the or the ends axially lengthened. Whenreleased from the radial constraint, or axial tension, the elastictethers will foreshorten the ends, forming double walled flanges wherethe saddle size (flange diameter, saddle length, saddle diameter) willconform exactly to the anatomy. Thus, the geometry will be“self-adjusting”. Reinforcement over the central saddle region is notnecessary but could be utilized if desired for other purposes.

Referring now to FIGS. 5A and 5B, a tissue anchor 40 comprises a tubularbody 42 which has both an elongated tubular configuration (as shown inFIG. 5A) and an axially foreshortened configuration with double-walledflanges 44, as shown in FIG. 5B. The tubular body 44 could either be ofthe self-expanding type or, alternatively, could require an axialcompressive force to foreshorten the body into the configuration of FIG.5B. In either case, the tissue anchor 40 will be provided with a lockingstructure including a plurality of axial bars 46 which lock over theends of the deployed tissue anchor 40, as illustrated in FIG. 5B.

Referring now to FIGS. 6A and 6B, a tissue anchor 50 comprises an anchorbody 52 which requires an axially compressive force in order toforeshorten the body to form the double-walled flanges 54, as shown inFIG. 6B. The axially compressive force is provided by a plurality oftethers 56 which extend through a lumen or central passage 58 of thebody 52 through the flange region and which then extend outwardly overthe central saddle region 60 before passing back into the interior ofthe body. By then pulling on the tethers 56 relative to the body 52, theflange regions will be axially compressed to radially expand, as shownin FIG. 6B, while and the central saddle region 60 may radially expandto an extent which depends on the braid configuration, the size andcompliance of the lumen through which the device passes, and the forceapplied to the tethers. After the flanges have been deployed, thetethers may be locked in place, typically by a locking device 64, suchas crimping pledgets, use of a unidirectional slide or other ratchetinglock device, or use of a slip-knot or a sliding element that relies onfriction to secure its position.

A tissue anchor 70, as illustrated in FIGS. 7A and 7B, comprises ananchor body 72 having a locking cylinder 74 in one end of the lumen orcentral passage 76. The anchor body 72 may be axially foreshortened bydrawing on the free end of the locking cylinder 74 and pulling thecylinder in the direction of the arrow until a locking end 78 of thecylinder engages the far end of the deployed flange 80. Not only doesthe cylinder 74 act as an element to foreshorten the anchor body 72, italso acts as the lock to hold the anchor body open and provides a smoothcylindrical surface for the lumen to permit fluid flow or provide otheraccess. Conveniently, the locking end 78 of the cylinder 74 may beprovided with notches or other apertures to allow that end to becollapsed within the lumen 76 and to snap back open as it is pulled pastthe flange 80 to which it will lock.

Referring now to FIGS. 8A and 8B, an exemplary tissue anchor or stent150 comprises a counterwound, braided stent body, typically formed froma polymer such as polypropylene, polyester, nylon, or PEEK; a metal,such stainless steel, nitinol, or eligiloy; a bioabsorbable material,such as polyglycolic acid, lactic acid, caprolactone, polydioxanone, cator bovine intestine; a natural fiber, such as silk or cotton; ormixtures, composites, or co-constructions of any of the above. Tethers166 are provided which are connected at the remote end 168 of the stent,and which, when drawn in the direction away from the duodenum or otheroriginating body lumen, will foreshorten the stent to create the flanges154, as described previously. Drawing the tethers 166 in the proximaldirection opens and maintains the central lumen 172 of deployed stent150 to provide the luminal conduit which allows flow between anatomicallumens, such as the gallbladder, GB and intestine. A reduced diametercentral region 170 is located between the flanges 154. The width of thecentral region 170 may be controlled optionally by placing a restrainingelement, such as a cylinder or struts 172 over the stent to preventradial expansion. Thus, the stent 150 will automatically adjust to thethickness of the luminal walls. A restraint is not needed since thetissue geometry, particularly the tract dilation either before or afteranchor placement, will provide a barrier which will restrain expansionof the central region and determine the length of the saddle region.

In another embodiment (not illustrated), the stent 150 can have proximaland distal ends connected centrally by an extensible material allowingthe deployed stent to facilitate apposition of opposing luminal wallsand minimize pressure necrosis.

Referring now to FIG. 9, in some instances it will be desirable toprovide a one-way flow element 180, such as a flat valve, within theinterior of the stent 150. By properly orienting the stent, the one-wayflow control element can then allow drainage from the gallbladder intothe intestines while substantially inhibiting or blocking reflux flowback from the stomach into the gallbladder. Additionally, the flowcontrol element 180 could serve as a restraint to define the centralregion 170 of the stent when expanded. Alternative valve designs includea sock valve placed within the interior or at the proximal end of theforeshortened anchor, a “duck bill” valve, a flapper valve, aspring-loaded ball valve, or other spring-loaded element, such as atapered pin or plug.

Use of the tissue anchors of the present invention for draining agallbladder will now be described. The biliary system of a patient (FIG.10) includes the gallbladder GB which is connected to the cystic duct CDwhich feeds into the common bile duct CBD. The common bile duct, inturn, feeds bile into the descending part of the duodenum DD. While thepresent invention will be described with particular reference toattachment between the gallbladder GB and the descending duodenum DD,the principles apply to connecting a variety of other luminalstructures, including the esophagus, the crus, the fundus, the bileduct, the intestines, and the like.

Referring now to FIG. 11, a system for connecting luminal walls andplacing a stent to establish a flow path therebetween is illustrated.This system 100 is particularly useful for connecting a wall of thegallbladder to an intestinal wall, such as the duodenal wall or astomach wall, but it will be appreciated that the system can find otheruses in establishing other anastomotic connections, such as between thebiliary duct including but not limited to the common bile duct, cysticduct and/or the pancreatic duct and the stomach, intestine or any partof the gastrointestinal tract. System 100 can also be used to create aconnection to any fluid collection including but not limited to apancreatic pseudocyst, abdominal fluid collections including ascites,pleural effusions and abscesses in any accessible location or the like.System 100 is also useful to create a connection between the urinarybladder and any part of the gastrointestinal tract.

The luminal wall connection system of the present invention comprises acatheter 112 including a catheter body 114 having a distal end 116 and aproximal end 118. The catheter body 114 has a lumen extendingtherethrough, with a distal port 120 of the lumen being visible in FIG.11. An inflatable balloon 122 is mounted on the distal end of thecatheter body 114 and an inflation lumen (not shown) is provided in thewall of the catheter body and connected to an inflation port 124 nearthe proximal end of the catheter body 114.

A needle 126 having a sharpened distal tip 128 is received within thelumen of the catheter body 114 and is slidably received so that it canbe selectively advanced from and/or retracted into the distal port 120,as illustrated in FIG. 11. A handle or grip 130 is provided at theproximal end of the needle 126 to facilitate manipulation.

An outer tubular member 136 is coaxially received over the catheter body114 and includes a distal end 138 having a distal port 140 through whichthe catheter body 114 projects. Proximal end 142 of the outer tubularbody 136 is connected to handle 144. Catheter body 114 extends throughthe handle, allowing the catheter of balloon 122 to be selectivelyextended and retracted relative to both the outer tube 136 and needle126.

The expandable tissue anchor/stent 150 is carried near the distal end138 of the outer tubular body 136. The stent is optionally expanded in avariety of ways, including balloon expansion, self-expansion (where thestent would be released from constraint), heat-induced expansion ofheat-sensitive alloy, such as nitinol, or the like. In the presentlypreferred embodiment, the stent 150 will comprise a polymer braid whichmay be foreshortened to induce radial expansion. This particular designwas described in more detail above with reference to FIGS. 8A and 8B.The handle 144 will include a thumb slide 152 for effecting expansion ofthe stent 150 typically by pulling on tethers attached to the stent, asdescribed below. A variety of other expansion mechanisms could beemployed, for example, by pushing on the proximal end of the stents withrods or other pushing elements while a distal portion of the stentremains constrained.

Referring now to FIGS. 12A-12E, deployment of the stent 150 to attachgallbladder wall GBW to an intestinal wall IW will be described.Initially, an endoscope E will usually be transorally introduced so thatit is within the intestines and can image the gallbladder to locate atarget site for the anastomotic connection, as illustrated in FIG. 12A.The endoscope will usually include at least a light source LS and afiber optic image cable, or in some instances a CCD or other miniaturecamera, or ultrasound transducer. The endoscope will also include aconventional working channel WC, as illustrated in broken line in FIG.12A.

Referring now to FIG. 12B, the luminal wall connection system 100 willbe introduced through the working channel WC so that the distal end 116of the catheter 114 is brought adjacent to the walls GBW and IW. Theneedle 126 may then be advanced through the walls to form an initialpenetration.

The uninflated balloon 122 will be advanced into the penetration,usually over the needle 126, as shown in FIG. 12C. The balloon may thenbe inflated, typically assuming a standard hot dog, top hat or dog bonepattern, said top hat having the distal end where the proximal anddistal ends are wider (e.g., have a larger diameter) than the centraland distal regions. Proximal movement of the top-hat balloon will pullthe GBW and the IW walls together. The penetration P is thus expandedprior to placement of the stent 150.

Referring to FIG. 12D, as an alternative to using balloon 122, thepenetration P can be expanded using a tapered dilator 160 which may beadvanced directly over the needle through the endoscope. Optionally, atapered dilator may be formed as a distal extension of the outer tubularmember 136 (not shown).

Referring now to FIG. 12E, after the penetration P has been expanded,the outer tubular member 136 will be advanced so that the stent 150 islocated in the expanded penetration. A stent 150 is then expanded, asshown in FIG. 12F, typically by foreshortening, as will be described inmore detail below. Preferably, the proximal and distal ends of the stent150 will be expanded or flared to form relatively large flange regions154 which act to tightly hold the gallbladder wall GBW and intestinalwall IW together to promote tissue knitting or ingrowth to inhibitleakage from either the gallbladder or the intestines. Once in place,the stent 150 forms a central lumen 152 (FIG. 12G) which provides a flowpath as indicated by the arrows in FIG. 12F from the gallbladder to theintestines. Following formation of a fistula or anastomosis the stentcan optionally be removed, the flow now being through a tissue fistulaorifice.

An alternate method is to follow the needle 126 with the simultaneousmovement of the outer tubular member 136 with stent 150 and balloon 122.The stent is then released from constraint, with proximal and distalflanges now expanding and holding the lumens together, this followed byballoon expansion of the saddle region of the stent by balloon 122 whichis inside the partially collapsed saddle region. This post-expansionmethod allows the anchor stent to hold the tissues together during tractdilation which is desirable. [Add figures and description?] FIG. 11 newversion will have stent on balloon Balloon is under saddle only

While the above is a complete description of the preferred embodimentsof the invention, various alternatives, modifications, and equivalentsmay be used. Therefore, the above description should not be taken aslimiting the scope of the invention which is defined by the appendedclaims.

What is claimed is:
 1. A method for approximating tissue and forming ananastomosis between a gallbladder and a duodenum or stomach, said methodcomprising: forming aligned penetrations in two adjacent tissue layersof two anatomical lumens, a first of the two anatomical lumens beingformed by the gallbladder and a second of the two anatomical lumensbeing formed by either the duodenum or the stomach; advancing a tissueanchor through said aligned penetrations, said anchor comprising a bodyhaving an axis and a woven filament braid, wherein said body is radiallyconstrained in an elongated tubular configuration while being advanced,and allowing the body to foreshorten into a preformed shape byself-expansion to cause a distal end and a proximal end of the body toeach deform into a double-walled flange structure leaving a cylindricalsaddle region therebetween, the saddle region having an open centrallumen therethrough to provide a flow path through the adjacent tissuelayers after the tissue anchor is in place, wherein the both walls ofeach flange structure lie perpendicular to the axis and the flangestructures press against the tissue layers with the saddle regiondisposed in the penetrations, wherein the both walls of each flangestructure and the cylindrical saddle region therebetween comprise acontinuous woven filament braid having an elastomeric material formedover the braid such that the material conforms to the body in both theelongated and foreshortened configurations, the material beingconfigured to prevent or inhibit tissue ingrowth, to minimize fluidleakage from the anatomical lumens and from the lumen of the saddleregion, and to allow the anchor to be removed after having beenimplanted for weeks, months, or longer, the material being configured toallow fluid flow through each flange structure and the cylindricalsaddle region between the anatomical lumens.
 2. A method as in claim 1,wherein the body is foreshortened to apply sufficient pressure to thetissue layers to hold them together without causing significant tissuenecrosis or adhesion.
 3. A method as in claim 2, wherein the appliedpressure is in the range from 0.025 psi to 2.5 psi.
 4. A method as inclaim 1, wherein forming and advancing comprise positioning a catheternear a target location on a tissue wall within one of said anatomicallumens, advancing a penetrating element from the catheter to form thepenetrations, and advancing the catheter through the penetrations toposition the tissue anchor therethrough prior to foreshortening.
 5. Amethod as in claim 1, wherein foreshortening comprises releasing theelongated tubular body from constraint so that the flanges self-expand.6. A method as in claim 1, wherein a valve, interposed within the body,provides a one way flow control allowing flow from the gallbladder andinto the duodenum or stomach without reflux.